1. Field of the Invention;
The present invention relates to a recording and/or reproducing apparatus and, more particularly, to a recording and/or reproducing apparatus of the type in which a tracking control is performed so as to enable a recording and/or reproducing head to follow a track on a recording medium.
2. Description of the Related Art
Recording and/or reproducing apparatus are known such as 8 mm VTRs and DATs (Digital Audio Tape Recorders). In this type of apparatus, a tracking control is essential for enabling a rotary head to correctly trace a track on a magnetic tape during reproduction. Various tracking control methods have been proposed and used, such as a method in which the speed of a capstan motor is controlled on the basis of a tracking error signal picked up from reproduced signals. In another known method, a magnetic head attached to the rotary drum is movably held by a bimorph element which is controlled in accordance with a tracking error signal so as to enable the head to trace the track.
The tracking control method relying upon the speed control of the capstan motor is disadvantageous in that a motor of high-torque and low-inertia type has to be used as the capstan motor because the speed change of the motor causes a change in the tape tension which acts as a load on the motor. The response frequency is as low as several hertz (Hz) even when such a motor is used. With this method, therefore, it has been materially essentially impossible to effect the tracking control particularly when a high response speed is required. For instance, this method cannot enable the head to follow the track when the track is warped or curved, which is experienced when a desired linearity is not attained between the tape and the rotary head.
The tracking control method which makes use of a bimorph element can provide a response frequency which is above several hundreds of hertz because only a light load is applied to the bimorph element which is required to effect a very small amount of movement. This method therefore can enable the head to well follow any warp or curve of the track. This method, however, suffers from the following disadvantage. Namely, the driving voltage for driving the bimorph clement is as high as several tens of volts to a thousand volts or higher. In order to apply this high voltage to the rotary drum, it is necessary to use brushes of a precious metal for electrical connection. It is difficult to maintain a stable electrical connection even with such brushes. Since the magnetic head is movably secured through the bimorph element, troublesome efforts are required for the mounting and adjustment of the magnetic head. High reproducibility of position of the magnetic head is a very important factor particularly in the recording operation. The movable magnetic head, therefore, is usable only for the purpose of reproduction. This means that a separate head has to be used for the recording purpose. Thus, the tracking control method relying upon the bimorph element undesirably raises cost of parts and requires laborious work in the assembly, with the result that the size and the production cost are increased.
On the other hand, there is an increasing demand for high recording density, particularly in digital VTRs which handle a good deal of information. In order to realize a track pitch of 10 .mu.m or smaller, a tracking which enables the head to follow any undulation of the track is necessary.